How to connect subsystems with different sample times in simulink

Hi there!

I am developing a solid state transformer using rectifier-DAB-inverter approach. Each subsystem has its own sample time, so i use different powerguis in the subsytems. The problem is that the model is not running as desired, yet each independent subsystem tested independently works perfect. what could be the problem?

someone mentioned about using the rate transition block but it cannot be connected between subsystems.

[Fangjun Jiang]

why can't insert rate transition block? Is this a physical (SimScape) model?

[mayaka moses]

yes it is a simscape model. Where do I connect the block? In the controller or the model? I have attached the images of the inverter, and rectifier_DAB. When I use simple duty cycle control, it works. The complex controller distorts everything. Maybe I need some delay somewhere?

[Fangjun Jiang]

When there is an error regarding sample time mismatch, it usually suggest a place to insert the rate transition block. You don't actually have that error. You just suspect that the integrated system does not perform as expected, yet each individual subsystem is tested.

It's so generic that I don't know how to help. One suggestion is to make all those individual subsystem an atomic subsystem.

[mayaka moses]

can I share my model so that you can look at it?

[mayaka moses]

I cannot use atomic subsystem because of the diodes in the system.

Answer 1

[Sabin]

Running the system at same (fastest) rate while having different PWM switching frequency and different sampling for the control algorithm should work. The model may be slightly slower but should perform as desired.

If Simscape technology (blue blocks) is used it is possible to use Network Couplers to split physical networks:

https://www.mathworks.com/help/simscape/ug/using-network-couplers-to-split-physical-networks.html